1. Field of the Invention
The present invention relates to a novel derailment protection apparatus that prevents a railway car (i.e. railroad car) or rolling stock under running state from a derailment.
2. Description of Related Art
Some derailment protection apparatuses are disclosed in patent documents, for example, Japanese patent application publications laid-open No. 09-272436 (patent document No. 1) and No. 2002-79941 (patent document No. 2).
The patent document No. 1, entitled “Derailment Preventing Device for truck” discloses that T type or I type retaining metals are attached to the wheel mount of a truck (rolling stock). One-side opened angular receiving metals are attached to the flange part of the truck main body.
By pinching the retaining metals on the wheel side by means of the retaining metals on the truck main body side, the retaining metals on the wheel side hit the retaining metals on the truck main body side, when a wheel swings to left and right relative to the progressing direction of the truck so as to correct the track automatically by the wheels themselves to make further running. In this case, a shock absorber provided on the inner surfaces of the receiving metals are hit by the retaining metals and on account of that repelling force, the wheels are changed in their mutually opposing directions and by repeating this action, track correction can be carried out automatically by the wheels themselves.
The patent document No. 2, entitled “Rolling Stock” discloses that a body is supported on a truck frame, axles and the wheels support the truck frame, and axle box suspensions support the axles by means of coil springs or rubber. Vertical load detectors are used between the axle box suspensions and the truck frame to detect vertical load. A comparison operator is used to perform comparative operation on detected results of the vertical load detectors, and an alarm is operated according to a detected result of the comparison operator. Thus, speed of the rolling stock is reduced, and the rolling stock is brought to an emergency stop.
In the derailment preventing device for truck (or derailment prevention apparatus) disclosed in the patent document No. 1, the retaining metals are attached to the wheel mount of a truck (rolling stock). One-side opened angular receiving metals are attached to the flange part of the truck main body. And the retaining metals and the receiving metals are fixed to the rolling stock,
During the rolling stock runs on a track with curved rails, the retaining metals and the receiving metals always hit together because the rolling stock receives a large lateral vibration.
Therefore, this derailment preventing device can not used in general rolling stock or train to run with comparatively high speed.
Furthermore, this derailment preventing device can not detect vertical and/or horizontal vibrations due to earthquake.
In the patent document No. 1, the vertical load detectors detect abnormal vibrations and the comparison operator performs comparative operation on detected results of the vertical load detectors. When the rolling stock receives the abnormal vibrations, the alarm is operated for indicating a command to reduce speed of the rolling stock is reduced or stop the rolling stock.
However, this device itself does not protect a derailment of the rolling stock.